Fig. 4 | Nature Communications

Fig. 4

From: Design and 22-step synthesis of highly potent D-ring modified and linker-equipped analogs of spongistatin 1

Fig. 4

A 16-step synthesis of the fully elaborated EF fragment of the spongistatins. Key steps include the double CM, double AD, and diastereoselective lactonization sequence that provides F-ring lactone 29 with five stereocenters in just three scalable steps, and the direct n-Bu4NBr-catalyzed complex fragment coupling alkallylation reaction to incorporate the chlorodiene sidechain (13 + 11 to 39). (DHQD)2PHAL hydroquinidine 1,4-phthalazinediyl diether, TMSCl trimethylsilyl chloride, PPTS pyridinium para-toluenesulfonate, TBSOTf tert-butyldimethylsilyl triflate, LiDBB lithium 4,4′-di-tert-butylbiphenylide

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